Americanah, By Chimamanda Ngozi Adichie

This satire of exile, race and ambition sees a strange America through a keen outsider's eyes

Perhaps there will always be meta-fictive moments in a novel which features writers as characters. There is one such notable moment in Americanah, a novel whose protagonist, Ifemelu, is a blogger recently arrived in America from Nigeria. She is with her black American boyfriend when his sister Shan – another writer – begins fulminating about the limited scope for race in American literature. "You can't write an honest novel about race in this country. If you write about how people are really affected by race, it'll be too obvious. Black writers… have two choices, they can do precious or they can do pretentious. When you do neither, nobody knows what to do with you."

Shan's rant is ironic given that Chimamanda Ngozi Adichie, an Orange Prize-winning Nigerian author now partly living in America, has dedicated her third novel to this very endeavour – to write a novel about race. The result is neither precious nor pretentious, though it is polemical in its angriest moments, and satirical at its best.

In part, it is a coming-of-age love story. The outspoken Ifemelu migrates from Lagos after winning a scholarship and leaves her boyfriend, Obinze. Neither can forget the passion of this first love. Their romantic trajectory offers the book a formal structure but it is Adichie's exploration of race and migration that is its heart. The alienation that both feel is acutely and authentically captured – Ifemelu's in America, Obinze's in England.

I wasn't black until I came to America, says Ifemelu, in her anonymous blog, which charts the displacement she feels and sees. Ifemelu's writing touches such a nerve in Obama's America that it transforms her fortunes: she begins on the margins, a pretty, dirty thing under a fake identity in the seamy immingrant underbelly; but thanks to the blog, as well as middle-class boyfriends, she begins to live a far more assimilated life.

Obinze, the son of a university professor, does not fare so well in London. After a series of blue-collar jobs, he is deported back to Lagos. They both learn what it means to be a foreigner, and that after this, their sense of "home" will forever lose its innocence. Ifemelu is branded (and herself feels) like an "Americanah" on her return – someone whose vision of Africa has been tainted by American culture.

Ifemelu's "outsider" observations in America are sharp and funny, though there are times when her righteous indignation leads her, through her blog, into overheated polemic. Despite this, the energy of Adichie's wit and satire outweighs these leaden didactic passages. She is particularly sharp on the social etiquette of American youth on campus, their shapeless sportswear ("When it comes to dressing well, American culture... has not only disregarded this courtesy of self-presentation, but has turned that disregard into a virtue"), and well-meaning white women who call certain other women "beautiful" when they simply mean "black".

Through the book's humour and its keen ear for dialogue, Americans begin to resemble the unfathomable Japanese "others" in Sofia Coppola's Lost in Translation, though for the most part Adichie manages not to reduce them into caricatures. Her Purple Hibiscus and Half of a Yellow Sun were both set in Nigeria. The nation, and its politics, is also present in Americanah, but seamlessly integrated into the psychology of its characters. Ostensibly a novel that shows us America from the outside, it also reveals something of Nigeria from the inside.